Resistance and friction from air within one or more of the moving components of a vehicle's propulsion system contributes to fuel efficiency losses and system degradation. These losses may be most pronounced within the transmission of the vehicle where air resistance losses are compounded by the high speed rotation of the systems components. In hybrid vehicles utilizing an electric motor and generator to provide torque to the engine and capture energy from regenerative braking, these losses may be even more pronounced due to high rate of conductor rotation.
Air resistance is proportional to the density of the air surrounding rotating components, thus losses may be reduced by decreasing this density. Density may be decreased by decreasing the amount of air within the case or enclosure containing the rotating system by creating a vacuum within the system. However, air passing over the rotating components provides cooling to the components to reduce degradation from overheating. By eliminating or reducing the volume of air coming into contact with the rotating components, the amount of heat absorbed for cooling is similarly reduced.
The inventors realized that by replacing the air within the components with a lower density gas, the air resistance could be decreased while still providing sufficient cooling. They further recognized that, in vehicles operating on natural gas, such as methane, the natural gas fuel may be used to provide cooling within the rotating component systems and may then be combusted within the engine with minimum waste or additional components.
In an embodiment, a hybrid vehicle with an engine combusting methane gas may deliver an amount of methane from the fuel tank to a transmission, generator, and/or motor case. Methane may then circulate though the system absorbing heat from rotation and may be evacuated from the system and either combusted or stored for later combustion. In this way, the rotating components of the transmission, generator, and/or motor may experience less flow-resistance-based friction, while still being effectively cooled. At the same time, the gas may still be re-used for combustion in the engine.
Further embodiments may inject or deliver an amount of methane in response to a desired amount of cooling within a system so that a minimum density may be achieved without compromising a desired cooling rate.
Still further embodiments may inject an amount of methane in response to a desired amount of resistance or resistance loss minimization. Methane may then be delivered or evacuated from a component to achieve the desired level of resistance.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.